There is known a laser emitter for emitting and displaying a laser line on a surface of a wall, ceiling or floor, which includes a rotation mechanism incorporated into the lower end region of the emitter main body, such that the laser line generated can be radiated over an angular range of 360°. In this instance, when the laser emitter has been installed, the marking is performed after manually operating the rotation mechanism so as to cause a coarse rotation of the emitter main body, by accurately aligning the laser line to the target site by a fine adjusting movement (cf. Patent Document 1: JP9-166436A).
This type of laser emitter requires an extremely delicate and precise adjustment when the laser line is to be manually focused to the target site by an operator, in particular when the laser line is generated so as to form a vertical line. Such an adjustment is a heavy burden to the operator. It is needless to say that the adjustment becomes less easy when the distance between the laser emitter and the light receiving element increases, even when a fine adjustment mechanism is provided.
In order to overcome such a problem, there is also known a laser emitter that can be rotated by a remote control and stopped when the laser line emitted from the laser emitter is detected by a light receiving element that has been previously arranged at the target site (cf. Patent Document 2: JP2000-230828A, and Patent Document 3: JP2001-191271A).
While the laser emitter of remote control type as mentioned above allows simplification of the manual operation and proved to be an effective measure for reducing the time required for marking, there is such disadvantage that the system becomes large due to the requirement for a driving source for the laser emitter.
Besides, while a coarse positioning adjustment is generally performed by manually rotating the emitter main body, particularly in the case of the laser emitter of remote control type, the driving system tends to be subjected to an excessive load when the emitter main body is manually rotated, which may cause mechanical failures.